1. Field of the Invention
The present invention relates to the field of pharmaceutical and vaccine compositions. More specifically, embodiments described herein relate to pharmaceutical and vaccine compositions, as well as related prophylactic and therapeutic methods, wherein the compositions comprise a glucopyranosyl lipid adjuvant (GLA).
2. Description of the Related Art
The immune system of higher organisms has been characterized as distinguishing foreign agents (or “non-self”) agents from familiar or “self” components, such that foreign agents elicit immune responses while “self” components are ignored or tolerated. Immune responses have traditionally been characterized as either humoral responses, in which antibodies specific for antigens are produced by differentiated B lymphocytes known as plasma cells, or cell mediated responses, in which various types of T lymphocytes act to eliminate antigens by a number of mechanisms. For example, CD4+ helper T cells that are capable of recognizing specific antigens may respond by releasing soluble mediators such as cytokines to recruit additional cells of the immune system to participate in an immune response. Also, CD8+ cytotoxic T cells that are also capable of specific antigen recognition may respond by binding to and destroying or damaging an antigen-bearing cell or particle. It is known in the immunological arts to provide certain vaccines according to a variety of formulations, usually for the purpose of inducing a desired immune response in a host.
Several strategies for eliciting specific immune responses through the administration of a vaccine to a host include immunization with heat-killed or with live, attenuated infectious pathogens such as viruses, bacteria or certain eukaryotic pathogens; immunization with a non-virulent infective agent capable of directing the expression of genetic material encoding the antigen(s) to which an immune response is desired; and immunization with subunit vaccines that contain isolated immunogens (such as proteins) from a particular pathogen in order to induce immunity against the pathogen. (See, e.g., Liu, 1998 Nature Medicine 4(5 suppl.):515.) For certain antigens there may be one or more types of desirable immunity for which none of these approaches has been particularly effective, including the development of vaccines that are effective in protecting a host immunologically against human immunodeficiency viruses or other infectious pathogens, cancer, autoimmune disease, or other clinical conditions.
It has long been known that enterobacterial lipopolysaccharide (LPS) is a potent stimulator of the immune system, although its use in adjuvants has been curtailed by its toxic effects. A non-toxic derivative of LPS, monophosphoryl lipid A (MPL), produced by removal of the core carbohydrate group and the phosphate from the reducing-end glucosamine, has been described by Ribi et al (1986, Immunology and Immunopharmacology of Bacterial Endotoxins, Plenum Publ. Corp., NY, p 407-419).
A further detoxified version of MPL results from the removal of the acyl chain from the 3-position of the disaccharide backbone, and is called 3-O-deacylated monophosphoryl lipid A (3D-MPL). It can be purified and prepared by the methods taught in GB 2122204B, which reference also discloses the preparation of diphosphoryl lipid A, and 3-O-deacylated variants thereof. For example, 3D-MPL has been prepared in the form of an emulsion having a small particle size less than 0.2 μm in diameter, and its method of manufacture is disclosed in WO 94/21292. Aqueous formulations comprising monophosphoryl lipid A and a surfactant have been described in WO9843670A2.
Bacterial lipopolysaccharide-derived adjuvants to be formulated in adjuvant combinations may be purified and processed from bacterial sources, or alternatively they may be synthetic. For example, purified monophosphoryl lipid A is described in Ribi et at 1986 (supra), and 3-O-deacylated monophosphoryl or diphosphoryl lipid A derived from Salmonella sp. is described in GB 2220211 and U.S. Pat. No. 4,912,094. 3D-MPL and the β(1-6) glucosamine disaccharides as well as other purified and synthetic lipopolysaccharides have been described (WO 98/01139; U.S. Pat. No. 6,005,099 and EP 0 729 473 B1, Hilgers et al., 1986 Int. Arch. Allergy Immunol., 79(4):392-6; Hilgers et al., 1987, Immunology, 60(1); 141-6; and EP 0 549 074 B1). Combinations of 3D-MPL and saponin adjuvants derived from the bark of Quillaja Saponaria molina have been described in EP 0 761 231 B. WO 95/17210 discloses an adjuvant emulsion system based on squalene, α-tocopherol, and polyoxyethylene sorbitan monooleate (TWEEN™-80), formulated with the immunostimulant QS21, and optionally including 3D-MPL. Despite the accessibility of such combinations, the use of adjuvants derived from natural products is accompanied by high production costs, inconsistency from lot to lot, difficulties associated with large-scale production, and uncertainty with respect to the presence of impurities in the compositional make-up of any given preparation.
Clearly there is a need for improved vaccines, and in particular for vaccines that beneficially contain high-purity, chemically defined adjuvant components that exhibit lot-to-lot consistency and that can be manufactured efficiently on an industrial scale without introducing unwanted or structurally undefined contaminants. The present invention provides compositions and methods for such vaccines, and offers other related advantages.